1. Field of the Invention
The present invention relates to a measuring unit and a valve for use therein. Particularly, the invention relates to a measuring unit for analysis of particles in a liquid sample.
2. Description of the Related Art
The following is prior-art devices related to the present invention.
(1) A biological fluid analyzing device for analyzing biological fluid by measuring optical characteristics of a sample, the device comprising: a sample receiving port and a pump connection port; at least one sample treating chamber, an optical measuring chamber and, optionally a waste liquid reservoir provided between the sample receiving port and the pump connection port; and a fluid pathway connecting the sample treating chamber, the optical measuring chamber and/or the waste liquid reservoir chamber (e.g., U.S. Pat. No. 5,681,529).
(2)A disposable measuring element comprising: a measuring channel with at least one optical or electrochemical sensor located therein; a first port provided at a first end of the measuring channel for connecting the measuring element to an analyzer; and a second port provided at a second end of the measuring channel for connecting the measuring element to a sample taking part, wherein a single common sealing element is provided for the first and second ports, and has first, second and third positions, wherein the first and second ends of the measuring channel are closed when the sealing element is at the first position, wherein the first end of the measuring channel is connected to the first port and the second end of the measuring channel is connected to a collecting tank provided in the measuring element for collecting liquid discharged from the measuring channel when the sealing element is at the second position, wherein the first end of the measuring channel is connected to a buffer tank provided in the measuring element and the second end of the measuring channel is connected to the second port when the sealing element is at the third position (e.g., U.S. Pat. No. 5,228,350).
With the aforesaid arrangements, the measuring unit (the biological fluid analyzing device or the measuring element) contaminated by a sample is discarded after use, so that a user can perform a sample analyzing operation safely and sanitarily.
However, the conventional measuring unit is not designed to accurately quantify a given sample. Therefore, it is difficult to accurately analyze biological fluid samples such as blood and urine, industrial particulate samples such as toner particles, and drink samples such as milk.
A conceivable approach to this problem is to preliminarily quantify the sample to be applied to the measuring unit. However, this approach additionally requires a device for quantifying the sample, which may also be contaminated by the sample.
Further, it is difficult to properly match the measuring unit with an additional sample quantifying and diluting device for accurate analysis of the sample with good reproducibility.